New research says crows instigate 97 percent of the altercations between them and Ravens in North America. Sciencealert.com says most of the incidents happen during the crows' breeding season from March to May. Researchers say It's likely crows are trying to protect their nests from ravens looking for an easy meal. Researchers add when incidents occurred outside the breeding season, it was mainly in winter. Findings show its mostly crows ganging up in small groups to drive off ravens.